JP2009183058A - Stator core fixing method and brushless motor - Google Patents

Abstract

Provided is a stator core fixing method capable of suppressing deformation of a stator core accompanying the fixing when the stator core and a ring member are fixed to a motor case.
A stator core 13 is inserted and disposed in a motor case 11 with a gap S in a radial direction, and then a ring member 15 is press-fitted or shrink-fitted to the outer peripheral surface of the motor case 11 corresponding to the position of the stator core 13. Fixed. The stator core 13 is fixed to the inner peripheral surface of the motor case 11 by contraction of the inner diameter of the motor case 11 by fixing the ring member 15.
[Selection] Figure 3

Description

  The present invention relates to a stator core fixing method for a motor case and a brushless motor using the stator core fixing method.

  A stator core of a brushless motor is generally fixed to the inner peripheral surface of a cylindrical motor case by press fitting or shrink fitting. The stator core is configured to include an annular portion and a plurality of teeth portions protruding radially inward from the annular portion, and conventionally, the stator core is configured by a plurality of divided cores in which the annular portion is divided for each individual teeth portion, There is one in which winding work is facilitated by winding a winding around a tooth portion before the divided core is formed into an annular shape. After the winding is wound, the split cores are annular, and adjacent split cores are fixed by welding, caulking, or the like at the cut portion of the annular portion, and the stator is fixed to the motor case. Has been.

  By the way, when the motor is driven to rotate, a magnetic attraction force and a repulsive force with the rotor magnet act on the stator core, so that distortion that expands and contracts the stator core occurs, which is one of the causes of vibration. In particular, the above-described split-type stator core has a structure in which such distortion of the stator core is more likely to occur, and there is a concern about an increase in vibration. Therefore, in order to suppress such distortion of the stator core, it has been considered to increase the rigidity of the motor case that supports the stator core.

  First, there is an aspect in which the plate thickness of the motor case is increased. In this aspect, a large press is required when a motor case is molded into a predetermined shape, for example, a bottomed cylindrical shape by drawing or the like. It was not a good idea because it required a processing machine. Next, for example, a completely double structure as in the motor case of Patent Document 1, or a ring member having an axial length equivalent to the stator core in a bottomed cylindrical motor case, for example, at the stator core fixing position. There is also an aspect in which the motor case is partially fitted to the outer peripheral surface to have a double structure.

As a first fixing method for fixing the stator core to the motor case having such a double structure, the stator core is fixed to the inner peripheral surface of the motor case in advance by press-fitting or shrink fitting, and then the stator core of the motor case is fixed. There is also a method of fixing the ring member to the outer peripheral surface of the position by press fitting or shrink fitting. As a second fixing method, a ring member is fixed in advance to the outer peripheral surface of the motor case at the stator core fixing position by press-fitting or shrink fitting, and then the stator core is fixed to the inner peripheral surface of the motor case at the ring member fixing position. There are methods of fixing by press fitting or shrink fitting.
JP 2002-1119030 A

  However, in the first fixing method, when the ring member is press-fitted or shrink-fitted, the inner diameter contracting force from the ring member acts on the motor case. In addition to shrinkage, the inner diameter shrinkage force of the ring member acts. Therefore, these two inner diameter contraction forces deform the stator core. In the second fixing method, since the ring member is fixed to the motor case first, the rigidity of the motor case is already high. For this reason, when the stator core is press-fitted or shrink-fitted into such a motor case, the reaction force from the motor case is large and a large inner diameter contracting force acts on the stator core, which also deforms the stator core. That is, in both fixing methods, the inner diameter contracting force acting on the stator core is large due to the influence of both the press-fitting or shrink-fitting of the stator core and the press-fitting or shrink-fitting of the ring member, which leads to deformation of the stator core. In particular, the large inner diameter contraction force acting on the above-described split type stator core is a serious problem in terms of its structure.

  As described above, the stator core is deformed at the time of fixing, and the larger the deformation, the more easily the air gap between the stator core and the rotor magnet becomes non-uniform, resulting in increased loss torque and cogging torque.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a stator core that can suppress deformation of the stator core accompanying the fixing when the stator core and the ring member are fixed to the motor case. An object of the present invention is to provide a brushless motor using the fixing method and the stator core fixing method.

  In order to solve the above problems, the invention according to claim 1 is characterized in that an annular stator core is fixed in a cylindrical motor case, a ring member is fixed at least on the outer peripheral surface of the stator core fixing position, A fixing method for fixing the stator core to the motor case at a position coinciding with the radial direction, the step of inserting and arranging the stator core with a gap in the radial direction in the motor case, and the arrangement of the stator core A step of press-fitting or shrink-fitting and fixing the ring member to the outer peripheral surface of the motor case corresponding to the position, and fixing the stator core to the inner peripheral surface of the motor case by shrinking the inner diameter of the motor case by fixing the ring member The gist is that

  In this invention, a stator core is inserted and arranged in the motor case with a gap in the radial direction, and then a ring member is press-fitted or shrink-fitted and fixed to the outer peripheral surface of the motor case corresponding to the arrangement position of the stator core. The stator core is fixed to the inner peripheral surface of the motor case by contraction of the inner diameter of the motor case by fixing the ring member. That is, when the stator core and the ring member are fixed to the motor case, only the ring member is press-fitted or shrink-fitted, so that the inner diameter contraction force received from the motor case when the ring member is fixed corresponds to a suitable fixing force. The deformation of the stator core can be prevented. In addition, with this fixing method, the press-fitting or shrink-fitting process, which increases the manufacturing cost, is only one step, so that the manufacturing cost can be reduced.

  According to a second aspect of the present invention, there is provided a stator core fixing method according to the first aspect, wherein the stator core is composed of a plurality of divided cores divided in the circumferential direction.

  In the present invention, the stator core is composed of a plurality of divided cores divided in the circumferential direction. Therefore, in such a divided stator core, the inner diameter received from the motor case during press-fitting or shrink-fitting due to its structure. Since it is easily deformed by the contraction force, it is significant to be applied to a split stator core.

  The invention according to claim 3 is the stator core fixing method according to claim 1 or 2, wherein the stator core and the ring member are made of metal and the motor case is made of resin, or the stator core and the motor case are The gist is that the metal and the ring member are made of resin.

  In the present invention, the stator core and the ring member are made of metal, and the motor case is made of resin. Alternatively, the stator core and the motor case are made of metal and the ring member is made of resin. That is, when the motor case or the ring member is made of resin, a vibration damping effect can be expected by bringing resin members having different rigidity into close contact with the metal member.

  According to a fourth aspect of the present invention, in the stator core fixing method according to any one of the first to third aspects, the motor case protrudes into each of an inner peripheral surface and an outer peripheral surface corresponding to the fixed position of the stator core. The gist is that a plurality of portions are formed in the circumferential direction, and the stator core and the ring member are respectively fixed via the protrusions.

  In the present invention, a plurality of protrusions are formed in the circumferential direction on each of the inner peripheral surface and the outer peripheral surface of the motor case corresponding to the fixed position of the stator core, and the stator core and the ring member are fixed through the respective protrusions. Thereby, since the contact area of the ring member with respect to the motor case becomes small, it is easy to press-fit or shrink-fit the ring member into the motor case. Moreover, since stress can be concentrated on each protrusion, the dimensional error of each member can be easily absorbed, and it can contribute to prevention of deformation of the stator core.

  According to a fifth aspect of the present invention, in the stator core fixing method according to the fourth aspect, the plurality of protrusions on the inner peripheral surface of the motor case and the plurality of protrusions on the outer peripheral surface of the motor case are in the circumferential direction. The gist is to be provided in accordance with the above.

  In this invention, the plurality of protrusions on the inner peripheral surface side of the motor case and the plurality of protrusions on the outer peripheral surface side coincide with each other in the circumferential direction, that is, the protrusions on the inner peripheral surface side and the protrusions on the outer peripheral surface side have an inner diameter. Since they are arranged in the radial direction, which is the contraction direction, dimensional management becomes easy.

  The invention according to claim 6 is the stator core fixing method according to claim 4, wherein the plurality of protrusions on the inner peripheral surface of the motor case and the plurality of protrusions on the outer peripheral surface of the motor case are in the circumferential direction. The gist is that they are provided in a shifted manner.

  In the present invention, the plurality of protrusions on the inner peripheral surface side of the motor case and the plurality of protrusions on the outer peripheral surface side are provided shifted in the circumferential direction, so that the vibration of the stator core that occurs during motor rotation driving is directly directed radially outward. Therefore, the vibration damping effect can be expected. Further, the inner diameter contracting force of the ring member can be distributed in the circumferential direction of the stator core via the motor case, which can contribute to prevention of deformation of the stator core.

  A seventh aspect of the present invention is the stator core fixing method according to any one of the fourth to sixth aspects, wherein the plurality of protrusions on the inner peripheral surface of the motor case are provided on a tooth portion provided on the stator core. The gist is to be arranged correspondingly.

  In the present invention, the plurality of protrusions on the inner peripheral surface side of the motor case are arranged corresponding to the tooth portions provided on the stator core. In other words, the stator core is composed of a tooth portion and an annular portion, and the tooth portion is long in the radial direction and has high rigidity in the same direction, so by arranging the protrusion corresponding to the tooth portion, This can contribute to the prevention of deformation of the stator core due to the inner diameter contraction force received. In addition, when the stator core is composed of split cores, the inner core contraction force received from the protrusions can be prevented from acting directly on the split portions because the stator core is split at the annular portion between adjacent teeth portions. This can contribute to prevention of deformation of the split stator core.

  The invention according to claim 8 uses the stator core fixing method according to any one of claims 1 to 7, and the stator core is fixed to the motor case at a position coinciding with the ring member in the radial direction. This is a brushless motor.

  According to the present invention, a brushless motor with a small deformation of the stator core can be provided by using the fixing method described in the above-mentioned claims for fixing the stator core of the brushless motor.

  According to the present invention, when fixing a stator core and a ring member to a motor case, a stator core fixing method capable of suppressing deformation of the stator core accompanying the fixing, and a brushless motor using the stator core fixing method are provided. Can be provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
FIG. 1 shows a brushless motor 10 of this embodiment. The brushless motor 10 of this embodiment is a motor for an electric power steering (EPS) device. The motor case 11 of the brushless motor 10 is made of metal and has a bottomed cylindrical shape, and a stator 12 is fixed at a predetermined position on the inner peripheral surface thereof.

  As shown in FIG. 2, the stator 12 is made of a magnetic metal having an annular portion 13a and a plurality of (in this embodiment, 12) teeth portions 13b that protrude radially inward from the annular portion 13a and that are equally spaced in the circumferential direction. The stator core 13 and the windings 14 wound around the respective tooth portions 13b are provided. The stator core 13 is composed of a plurality (12) of divided cores 13x in which the annular portion 13a is divided at an intermediate position between adjacent tooth portions 13b for each tooth portion 13b, and the divided core 13x is annular. The winding 14 is wound around the tooth portion 13b before being set. Then, after the winding 14 is wound, the divided cores 13x are formed in an annular shape, and adjacent divided cores 13x are fixed to each other by welding, caulking, or the like at the cut portion of the annular portion 13a. A stator core 13) is fixed to the motor case 11.

  Further, in the motor case 11, a metal ring member 15 that is slightly longer in the axial direction than the stator core 13 is fixed to the outer peripheral surface of the fixing position of the stator core 13. That is, in the motor case 11 of the present embodiment, the fixing position of the stator core 13 has a partially double structure, the rigidity of the fixing position of the stator core 13 is partially increased, and the rotor 16 that is generated when the motor is driven to rotate. The expansion and contraction of the stator core 13 due to the magnetic attractive force and repulsive force with the magnet 19 is suppressed.

  As shown in FIG. 1, a rotor 16 is accommodated inside the stator 12. The rotor 16 includes a rotating shaft 17, a rotor core 18 fixed to the rotating shaft 17, and a magnet 19 fixed to the outer peripheral surface of the rotor core 18. The rotor 16 is an end frame in which a predetermined end portion of the rotating shaft 17 is attached to an opening of the motor case 11 by a bearing 20a in which the base end portion of the rotating shaft 17 is installed at the center of the bottom of the motor case 11. The magnet 19 is rotatably supported by the bearing 20b installed in the center part of 21 so that it may oppose the stator 12 (stator core 13) to radial direction.

  A sensor rotor 22 a is fixed to the end frame 21 side of the rotating shaft 17, and a sensor stator 22 b is fixed to the end frame 21, and a resolver 22 is configured by these. The resolver 22 outputs a detection signal corresponding to the rotational position of the rotor 16 and generates a drive current to be supplied to the stator 12 (winding 14) based on the rotational position detection signal. And after accommodating the stator 12, the rotor 16, and the resolver 22 in the motor case 11, the end frame 21 is attached to the opening part of this motor case 11, and the brushless motor 10 is comprised.

Next, a method of fixing the stator core 13 (stator 12) and the ring member 15 to the motor case 11 in the brushless motor 10 having such a configuration will be described.
In the present embodiment, as shown in FIG. 3A, the stator core 13 around which the winding 14 is wound is inserted into a predetermined position in the motor case 11 first. At this time, before the stator core 13 is fixed to the motor case 11, the outer diameter of the stator core 13 (annular portion 13 a) is set slightly smaller than the inner diameter of the motor case 11. A predetermined gap S is formed between the inner peripheral surface of the motor case 11.

  Next, the stator core 13 is positioned in the motor case 11 in a loosely fitted state, and the ring member 15 is fixed to the outer peripheral surface of the motor case 11 corresponding to the arrangement position of the stator core 13 by press fitting or shrink fitting. Then, as shown in FIG. 3B, the inner diameter of the motor case 11 is contracted by press fitting or shrink fitting of the ring member 15, and the inner peripheral surface of the motor case 11 presses the stator core 13 due to the contraction of the inner diameter. It is fixed to the inner peripheral surface of the motor case 11 with a suitable fixing force. In other words, it is set to the dimension of the gap S that provides such a suitable fixing force. Thus, the ring member 15 is fixed to the motor case 11 and the stator core 13 in the motor case 11 is simultaneously fixed by press-fitting or shrink-fitting the ring member 15.

  As a result, when the stator core 13 and the ring member 15 are fixed to the motor case 11, only the ring member 15 is press-fitted or shrink-fitted, so that the inner diameter received from the motor case 11 when the ring member 15 is fixed to the stator core 13. The contraction force is reduced to a suitable fixing force, and deformation such as inner diameter contraction of the stator core 13 is prevented. In addition, with this fixing method, the press-fitting or shrink-fitting process, which increases the manufacturing cost, is only one step, so that the manufacturing cost can be reduced.

Next, characteristic effects of the present embodiment will be described.
(1) In the present embodiment, the stator core 13 is inserted and arranged in the motor case 11 with a gap S in the radial direction, and then the ring member 15 is provided on the outer peripheral surface of the motor case 11 corresponding to the arrangement position of the stator core 13. Press fit or shrink fit. The stator core 13 is fixed to the inner peripheral surface of the motor case 11 by contraction of the inner diameter of the motor case 11 by fixing the ring member 15. That is, when the stator core 13 and the ring member 15 are fixed to the motor case 11, only the ring member 15 is press-fitted or shrink-fitted, so that the inner diameter contraction received from the motor case 11 when the ring member 15 is fixed to the stator core 13. The force can be reduced to a suitable fixing force, and the deformation of the stator core 13 can be prevented. Therefore, the brushless motor 10 with a small deformation of the stator core 13 can be provided.

  (2) In the fixing method of the present embodiment, since the press-fitting or shrink-fitting process is only one step when the ring member 15 is fixed, the press-fitting or shrink-fitting process that increases the manufacturing cost can be configured to be small, and the manufacturing cost can be reduced. be able to. Therefore, it can contribute to the cost reduction of the brushless motor 10.

  (3) Since the stator core 13 of the present embodiment is composed of the divided cores 13x divided into a plurality in the circumferential direction, such a divided stator core 13 is press-fitted or shrink-fitted due to its structure. Since it is easy to be deformed by the inner diameter contraction force sometimes received from the motor case 11, it is significant to apply the above fixing method to the split stator core 13.

In addition, you may change embodiment of this invention as follows.
In the above embodiment, neither magnetic nor nonmagnetic properties of the motor case 11 and the ring member 15 made of metal are particularly mentioned, but both the motor case 11 and the ring member 15 are made of magnetic metal, and the magnetic path is formed together with the stator core 13. It may be configured. If the magnetic path of only the stator core 13 is sufficient, the motor case 11 and the ring member 15 may be made of nonmagnetic metal. Further, the motor case 11 may be made of a magnetic metal and the ring member 15 may be made of a nonmagnetic metal.

  Furthermore, the stator core 13 and the ring member 15 may be made of metal and the motor case 11 may be made of resin, or the stator core 13 and the motor case 11 may be made of metal, and the ring member 15 may be made of resin. That is, when the motor case 11 or the ring member 15 is made of resin, a vibration damping effect can be expected by bringing resin members having different rigidity into close contact with the metal member.

  In the above embodiment, the stator core 13, the motor case 11, and the ring member 15 are in surface contact with each other. For example, as shown in FIGS. 4 (a) to 4 (c), the inner peripheral surface and the outer peripheral surface of the motor case 11. The protrusions 11a and 11b may be formed on the surface.

  In the embodiment shown in FIG. 4A, a plurality of protrusions 11a and 11b are formed in the circumferential direction on the inner peripheral surface and the outer peripheral surface of the motor case 11 corresponding to the fixed position of the stator core 13, respectively. The protrusions 11a and 11b are arranged at equal intervals corresponding to the teeth 13b, and the protrusions 11a on the inner peripheral surface side and the protrusions 11b on the outer peripheral surface side are aligned in the circumferential direction. Each protrusion 11a, 11b is formed to be continuous in the axial direction, for example, by the axial length of the stator core 13 and the ring member 15. And the stator core 13 and the ring member 15 are each fixed via these protrusion part 11a, 11b.

  Thereby, since the contact area of the ring member 15 with respect to the motor case 11 becomes small at the protrusion 11b, it is easy to press-fit or shrink-fit the ring member 15 into the motor case 11. Further, since stress can be concentrated on each of the protrusions 11a and 11b, the dimensional error of each member can be easily absorbed, and the deformation of the stator core 13 can be prevented.

Further, since the protrusion 11a on the inner peripheral surface side and the protrusion 11b on the outer peripheral surface side coincide with each other in the circumferential direction, that is, the protrusions 11a and 11b are aligned in the radial direction which is the inner diameter contraction direction, the dimensional management is easy. .
Further, since the tooth portion 13b is long in the radial direction and has high rigidity in the same direction, the stator core due to the inner diameter contracting force received from the protrusion 11a is provided by arranging the protrusion 11a on the inner peripheral surface side corresponding to the tooth portion 13b. 13 can prevent deformation. Further, since the stator core 13 is of a split type and is divided by an annular portion 13a between adjacent tooth portions 13b, it can prevent the inner diameter contracting force received from the protrusion 11a from acting directly on the divided portion. This can contribute to the prevention of deformation of the stator core 13 which is a split type.

  Further, as shown in FIG. 4B, the protrusion 11b on the outer peripheral surface side is in the circumferential direction so as to be an intermediate position between the adjacent protrusions 11a with respect to the protrusion 11a on the inner peripheral surface side of the motor case 11. It may be provided to be shifted.

  In this way, the vibration of the stator core 13 generated during motor rotation driving does not directly go radially outward, so that a vibration damping effect can be expected. In addition, the inner diameter contraction force of the ring member 15 can be dispersed in the circumferential direction of the stator core 13 via the motor case 11, which can contribute to prevention of deformation of the stator core 13.

  Moreover, as shown in FIG.4 (c), the protrusion provided in the motor case 11 may be only the protrusion 11a on the inner peripheral surface side, and the protrusion 11b on the outer peripheral surface side may be omitted. Alternatively, the protrusion 11a on the inner peripheral surface side may be omitted, and only the protrusion 11b on the outer peripheral surface side may be provided.

-In above-mentioned embodiment, although the stator core 13 was comprised by the split type using the split core 13x, you may comprise by integral type.
In the above embodiment, the present invention is applied to the brushless motor 10.

  In the above embodiment, the brushless motor 10 is used for an electric power steering device, but may be other devices.

It is an axial sectional view of the brushless motor in this embodiment. It is a radial direction sectional view of a brushless motor. (A) (b) is explanatory drawing explaining the fixing method of the stator core and ring member with respect to a motor case. (A)-(c) is sectional drawing explaining the fixing | fixed part of the stator core and ring member with respect to the motor case in another example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Motor case, 11a, 11b ... Projection part, 13 ... Stator core, 13b ... Teeth part, 13x ... Divided core, 15 ... Ring member, S ... Gap.

Claims (8)

An annular stator core is fixed in a cylindrical motor case, a ring member is fixed at least to the outer peripheral surface of the stator core fixing position, and the stator core is fixed to the motor case at a position that coincides with the ring member in the radial direction. Its fixing method,
Inserting and arranging the stator core with a gap in the radial direction in the motor case;
The ring member is press-fitted or shrink-fitted and fixed to the outer peripheral surface of the motor case corresponding to the arrangement position of the stator core, and the stator core is fixed to the inner peripheral surface of the motor case by shrinkage of the inner diameter of the motor case by fixing the ring member. And fixing the stator core. A stator core fixing method comprising: The stator core fixing method according to claim 1,
The stator core fixing method, wherein the stator core is composed of a plurality of divided cores divided in the circumferential direction. In the stator core fixing method according to claim 1 or 2,
The stator core and the ring member are made of metal and the motor case is made of resin, or the stator core and the motor case are made of metal, and the ring member is made of resin. Fixing method. In the fixing method of the stator core of any one of Claims 1-3,
A plurality of protrusions are formed in the circumferential direction on each of the inner peripheral surface and outer peripheral surface of the motor case corresponding to the fixed position of the stator core, and the stator core and the ring member are fixed through the respective protrusions. A stator core fixing method as a feature. In the stator core fixing method according to claim 4,
The stator core fixing method, wherein the plurality of protrusions on the inner peripheral surface of the motor case and the plurality of protrusions on the outer peripheral surface of the motor case are provided so as to coincide with each other in the circumferential direction. In the stator core fixing method according to claim 4,
The stator core fixing method, wherein the plurality of protrusions on the inner peripheral surface of the motor case and the plurality of protrusions on the outer peripheral surface of the motor case are provided shifted in the circumferential direction. In the fixing method of the stator core of any one of Claims 4-6,
The method of fixing a stator core, wherein the plurality of protrusions on the inner peripheral surface of the motor case are arranged corresponding to teeth portions provided on the stator core.   A brushless motor, wherein the stator core is fixed to the motor case at a position coinciding with the ring member in a radial direction using the stator core fixing method according to any one of claims 1 to 7. .

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